RT Journal Article SR Electronic T1 Tidal changes on CT and progression of ARDS JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP thoraxjnl-2016-209833 DO 10.1136/thoraxjnl-2016-209833 A1 Maurizio Cereda A1 Yi Xin A1 Hooman Hamedani A1 Giacomo Bellani A1 Stephen Kadlecek A1 Justin Clapp A1 Luca Guerra A1 Natalie Meeder A1 Jennia Rajaei A1 Nicholas J Tustison A1 James C Gee A1 Brian P Kavanagh A1 Rahim R Rizi YR 2017 UL http://thorax.bmj.com/content/early/2017/06/19/thoraxjnl-2016-209833.abstract AB Background Uncertain prediction of outcome in acute respiratory distress syndrome (ARDS) impedes individual patient management and clinical trial design.Objectives To develop a radiological metric of injurious inflation derived from matched inspiratory and expiratory CT scans, calibrate it in a model of experimental lung injury, and test it in patients with ARDS.Methods 73 anaesthetised rats (acid aspiration model) were ventilated (protective or non-protective) for up to 4 hours to generate a spectrum of lung injury. CT was performed (inspiratory and expiratory) at baseline each hour, paired inspiratory and expiratory images were superimposed and voxels tracked in sequential scans. In nine patients with ARDS, paired inspiratory and expiratory CT scans from the first intensive care unit week were analysed.Results In experimental studies, regions of lung with unstable inflation (ie, partial or reversible airspace filling reflecting local strain) were the areas in which subsequent progression of injury was greatest in terms of progressive infiltrates (R=0.77) and impaired compliance (R=0.67, p<0.01). In patients with ARDS, a threshold fraction of tissue with unstable inflation was apparent: >28% in all patients who died and ≤28% in all who survived, whereas segregation of survivors versus non-survivors was not possible based on oxygenation or lung mechanics.Conclusions A single set of superimposed inspiratory–expiratory CT scans may predict progression of lung injury and outcome in ARDS; if these preliminary results are validated, this could facilitate clinical trial recruitment and individualised care.